atomic number = # of protons = # of electrons (neutral atom)
DESCRIPTION
INTRO / REVIEW. Atomic mass. Atomic number = # of protons = # of electrons (neutral atom). Carbon has an atomic number of 6, which means it has 6 ________ in its nucleus and 6 __________ orbiting around the nucleus. protons. electrons. Organization of Your Periodic Table. - PowerPoint PPT PresentationTRANSCRIPT
Atomic number = # of protons = # of electrons (neutral atom)
Atomic mass
Carbon has an atomic number of 6, which means it has 6 ________ in its nucleus and 6 __________ orbiting around the nucleus.
protonselectrons
Organization of Your Periodic Table
He, Ne, and Ar are in the same ___________.
C, N, and O are in the same ___________.
P E R I O D SGROUPS
Page 168-169
Organization of Your Periodic Table
Atomic mass
*** Atomic # ***Similar properties:
Reactivities
Electron Configurations (groups)
Families
Get out your color coded periodic table!!!
Metals
Excellent conductors (Sea of electrons) even as solids
Mobile electrons
Metals are malleable and ductile
Can be pounded into sheet
Can be pulled into wire
Alkali Metals
Similar properties:
Group # 1
Reactive
Good Conductors
Alkaline Earth Metals
Similar properties:
Group # 2
Reactive – but less than alkali
Good Conductors
Metals
Excellent conductors (Sea of electrons) even as solids
Mobile electrons
Metals are malleable and ductile
Can be pounded into sheet
Can be pulled into wire
Noble Gases
Similar properties:
Group # 18
NON-reactive
Gases
Full outer shells!!!
Halogens
Similar properties:
Group # 17
Very reactive
Fluorine and Chlorine = gases
7 valence electrons
Transition metalsSimilar properties:
Generally least reactive metals
Tricky valence (can change from the expected)
Mostly form +1, +2, and +3 ions
Red = ?Green = ?
Blue = ?
Good Conductors = ?
Inert elements = ?
Review1. What element is in Group 2,
Period 3?
2. Name an element in Group 3
3. How many valence electrons in Xe?
4. Give me an element with 1 valence electron.
Periodic TrendsAtomic radius:- Measure of size – radius of an atom
- Atoms with more electrons do NOT necessarily have a larger atomic radius
Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius
Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius
1. Atoms get larger going down a group.
2. Atoms get smaller going across a period
So why?...
Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius
As you move across a period, # of protons increases and outermost energy level stays the same, attractive force between elecs. and pros. pulls the atom tighter (closer to nucleus)
Periodic TrendsWhat’s bigger:
B or Al
B or N
N or Zn
C or Cl
Periodic TrendsIonization energy – energy needed to remove one electron from an atom
Li → Li+ + e-
… indication of how strongly an atom holds onto its outermost elecs.
Periodic TrendsThe graph on page 178 shows how ionization energies vary with atomic #
What element does the black point at (10, 2100) represent?
With respect to the periodic table ionization energies show 2 important trends…
Periodic TrendsWith respect to the periodic table ionization energies show 2 important trends…
1. Decrease as you move down a group
2. Increase as you move left to right across a period
Periodic Trends
How does the ionization energy trend compare to the atomic radius trend?
Does this make sense?
Periodic Trends
O
Be
Be
Cl
------
What’s bigger: ↑er I. E.:
O or C
Be or Ca
Na or Be
Cl of Al
Ca or B+3
IN NOTES
Periodic Trends
O
Mg
Be
Cl
------
What’s bigger: ↑er I. E.:
O or B
Mg or Sr
K or Be
Cl of Si
Sr or Al+3
IN NOTES
Periodic TrendsSuccessive Ionization energies (removing more than one electron from an atom):
- The 2nd > 1st, the 3rd > 2nd, the 4th > the 3rd
- but if you look at the I. E. s there is usually a large jump. Where? PAGE 178
Periodic TrendsHow does atomic radius change?
Why?
How does ionization energy change?
Why?
With respect to the periodic table ionization energies show 2 important trends…
1. Decrease as you move down a group
2. Increase as you move left to right across a period
How does the ionization energy trend compare to the atomic radius trend?
Does this make sense?
What’s bigger: ↑er I. E.:
O or K
Mg or Mg+2
S-2 of F-1
Octet Rule = ?
Octet rule – Atoms tend to gain, lose, or share electrons in order to acquire a full set of valence electrons (8) [2 for H, He, Li, Be, + B]
What is electronegativity?
How does it increase on the p. t. ?
In this bond: Mg—O, which way do
elecs. Shift? WHY?
Electronegativity – ability to attract electrons in a bond
O, > electroneg.
Bigger down a group and smaller across a period
How does atomic radius change?
Why?As you move down a group, there are additional energy levels
As you move across a period there are additional protons pulling the electron in tighter
Negative ions get bigger
Positive ions get smaller
How does ion size change?
Why?
Negative ions gain electrons
Positive ions lose electrons
Opposite of size (atomic radius)
How does ionization energy change?
Why?
Electrons are closer to the nucleus and held tighter in smaller atoms
Away from the middle
How does reactivity change?
Why?
Atoms on the outside of the p.t. are closer to achieving the octet rule and so more reactive
Up and to the right (Fr to F)
How does electronegativity change?
Why?
Elements on the right side of the periodic table want electrons to satisfy the octet rule